Examples of symmetries

In particle physics, examples of Wigner vs Nambu-Goldstone, ignoring gravity the only exact internal symmetry in the standard module is
\( (B\# – L\#) \), believed to be a \( U(1) \) symmetry in Wigner mode.

Here \(B\#\) is the Baryon number, and \( L\# \) is the Lepton number. Examples:

\( B(p) = 1 \), proton.

\( B(q) = 1/3 \), quark

\( B(e) = 1 \), electron

\( B(n) = 1 \), neutron.

\( L(p) = 1 \), proton.

\( L(q) = 0 \), quark.

\( L(e) = 0 \), electron.

The major use of global internal symmetries in the standard model is as “approximate” ones. They become symmetries when one neglects some effect( “terms in \( \LL \)”).
There are other approximate symmetries (use of group theory to find the Balmer series).